CHAPTER- 3 MOTIONS OF THE EARTH

Q1. Answer the following questions briefly.

  1. What is the angle of inclination of the earth’s axis with its orbital plane?

Ans.  661/2 degree.

B) define rotation and revolution.

Ans. Rotation- the movement of the earth on its axis is known as rotation.

         revolution- the movement of the earth around the sun in a fixed path or orbit is known as   revolution.

  • What is a leap year?

Ans. The year in which february is of 29 days instead of 28 days is called a leap year.

  • Differentiate between the summer solstice and winter solstice.

Ans. Summer solstice-

  • In the northern hemisphere the longest day and the shortest night occur on 21st june.
  • At the same time in southern hemisphere it occurs the shortest day and the longest night.
  • This position of the earth is called summer solstice.

Winter solstice-

  • In the northern hemisphere the shortest day and the longest night occur on 22nd december.
  • At the same time in southern hemisphere it occurs the longest day and the shortest night.
  • This position of the earth is known as winter solstice.

E)what is an equinox?

Ans.

  • On 21st march and 23rd september direct rays of the sun fall on the equator.
  • Neither of the poles is tilted towards the sun.
  • Therefore the entire earth experiences equal days and equal nights.
  • This phenomenon is called an equinox.

F) why does the southern hemisphere experience winter and summer solstice in different times than  that of the northern hemisphere?

Ans. We experience these differences due to the position of the earth.

G) why do poles experience about six months day and six months night?

Ans. The axis of the earth is tilted due to the sun continuously either shines or cannot be seen for a long time here. So the poles remain under the same stage for a much longer time that is six months.

Q2. Tick the correct answer.

A) the movement of the earth around the sun is known as-

I) rotation

ii) revolution     

Iii) inclination 

B) direct rays of the sun fall on the equator on-

i) 21st march      

Ii)21st june

Iii) 22nd december

C) christmas is celebrated in summer in-

I) japan

Ii) india

iii) australia                           

D) cycle of the seasons is caused due to –

I) rotation

ii) revolution   

Iii) gravitation

Q3. Fill in the blanks.

A) a leap year has 366 number of days.

B) the daily motion of the earth is rotation.

C) the earth travel around the sun in elliptical orbit.

D) the sun rays fall vertically on t he tropic of cancer on 21st june.

E) days are shorter during winter season.